Selling in units and cases sizes

Hi
I am hoping someone can help me, as I am not sure on the best way to proceed and whether I need an extension ?
I am running 1.5.6.4
I would like the public to be able to visit my site and buy individual items at the RRP price.
I would like trade customers to login and see items in cases at the Trade price. They would buy in whole cases rather than individual items. Typically a case contains 6 or 12 items.
I don't want the public to see or be able to buy in cases and vice versa with the Trade customers.
Any guidance would be appreciated

Well, this one could be of help with such!
Good Luck!
Ernie
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Quantity Add In Multiples of Minimum Quantity 1.5x
Suppose you have a product with minimum quantity as 3.
Opencart version support: All versions on 1.5.x
Then this extension will only allow quantity to be added in steps of 3.
Like 3,6,9,12,15 etc.
Will work with all themes. No core files changed.
Email: support@cartbinder.com
https://www.opencart.com/index.php?rout ... n_id=24051
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